Cold downdraughts.

Standards to keep out the draught.

             

Treating the cause - not the symptoms.

Finding a solution to the problem of draughty buildings can be fraught with difficulty. Very often only the symptoms are apparent and the root cause can be difficult to identify. All too often a 'try and see' approach is adopted until finally, if luck prevails, a successful solution is found. The design team addressing the problem of a draughty mall at a shopping centre in Shrewsbury adopted a different approach. The possible causes were identified using site knowledge and Computational Fluid Dynamics. A 'blind' analysis of site data was then undertaken by an independent statistician ie.

Effect of airflow direction on human perception of draught.

Forty subjects, 20 women and 20 men, were exposed to airflows from five different directions: horizontally towards the front, the back, and the left side and vertically upwards and downwards. The subjects were exposed to stepwise increased air velocities ranging from less than 0.10 m/s to 0.40 m/s at three temperature levels 20, 23 and 26°C. The results showed that airflow direction has an impact on perceived discomfort due to draught. At 20°C and 23°C, airflow from below was perceived as most uncomfortable followed by airflows towards the back and front.

Local thermal discomfort caused by fan convectors.

           

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